This invention relates to a machine for shaping a workpiece and more particularly, to an improved air slide for precisely determining the relative position between a grinding tool and the holder for a workpiece.
Precision optical elements may be formed in molds having a precise configuration. U.S. Pat. No. 4,481,023 Marechal and Maschmeyer describes the molding of a glass lens having dimensional tolerances finer than 0.1% and surface figure tolerances finer than 0.2 .lambda./cm in the visible range of the radiation spectrum. The molds for forming such lenses must have a very precise configuration.
The mold must have a good surface finish, be inert to the glass, and have sufficient rigidity to retain the surface figure at pressing temperature. Mold materials which are suitable for use include 400 series stainless steels, electroless nickel, beryllium nickel alloys, tungsten carbide, alloys of noble metals such as platinum, rodium, and gold, and fused silica.
Heretofore, some such molds of specific composition have been fabricated by a point diamond turning operation, as disclosed in European Patent Application Publication No. 0011331. However, harder materials such as stainless steels cannot be fabricated into molds by single point diamond turning machines.
It is an object of the present invention to provide a grinding machine which can be used to fabricate work pieces, such as molds, from very hard materials such as stainless steels, tungsten carbide and ceramics.
It is another object of the present invention to prevent the intrusion of foreign material into an air slide which is used to position a tool.